How would you feel about your Dad still being in contact with your ex?

[NoEffingWay]

At handover today, ex-h casually mentioned he had been chatting with df. I asked him not to, we have been divorced for nearly 6 months now, and they weren't friends when we were together. My df changed the subject when I asked him to call me and not ex-h if he has questions. It makes me feel a bit like my df has gone behind my back a bit, but also what the hell are they talking about?!

Unless there's a massive backstory here where the divorce was entirely down to him and you were completely blameless, why on earth shouldn't your dad chat to his ex son in law?

And how is it any of your business what they talk about?

they weren't friends when we were together

This would (and has) made me very uncomfortable too.

Sorry you're having to deal with co-parenting, it can't be easy. Isn't it OK, in fact good for your DC(s), if their granddad and their dad are communicating though? As PP has said, assuming there's no other significant info here about the circumstances of your split and your ex's behaviour of course? I'm trying to think about it from your parents' and kids' pov, that they might feel it helps the transition (as the situation is quite new) if they maintain as normal relationships as possible. But like I said, no-one else knows your ex so you may have excellent reasons to ask them to keep away from him.

Mine was, and I felt unbelievably betrayed. My exh was incredibly abusive but having divorced my mum, my dad tried everything he could to keep us together for the sake of the dc. My dad was unaware of the abuse - it was emotional, financial and coercive, I often think if I'd have been battered even once I'd have had his complete support - until I had to call the police and we ended up in court 3 times.

By god it stung, and my ex used to rub my face in it constantly. My dad has seen the light now though, and supports me 100%

It wasn't an abusive relationship but ex-h was keen on controlling any situation and struggled with anything that he felt he didn't have 100% control over. It was oppressive and a bit dominating.
I don't feel that co-parenting with my ex has much to do with my Dad, he doesn't have much input into the DC on a daily basis. This wasn't part of my original post so a little confused here?
Ex-h has constantly tried to influence my life post divorce and I finally felt that he understood I don't want to be in each others pockets i.e we aren't married anymore.
I want there to be a healthy separation of knowledge about the others life, and this feels intrusive and unwelcome.

Google Coercive Control, OP.

From your description, I think your exh does sound abusive. Google also "post separation abuse".

Fifteen years later, he's still sending my parents an anniversary card and trying to get invites to family events. This is based on the fact that I left him, so he's entitled as he's done nothing wrong.

On the other hand, his family pretend I've died and have physically edited me out of video footage so that my children appear to have been brought up motherless.

I can't see any reason for them to be in contact and I would feel a bit betrayed by my dad tbh.